<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style type="text/css">
*{
	padding: 0;
	margin: 0;
}
	.menu{
		width: 200px;
		height: 40px;
		border: 3px solid blue;
		margin: 10px auto;
	}
	.menu .title{
		display: block;
		width: 200px;
		height: 40px;
		background: orange;
		line-height: 40px;
		font-size: 15px;
		text-align: center;
	}
	.menu .list{
		width: 200px;
		background: #eee;
		line-height: 1.5em;
		list-style: none;
		display: none;
	}
</style>
<script type="text/javascript" src="jquery-1.7.2.min.js"></script>
<script type="text/javascript">
	// 能用this的时候，就尽量用this
	// 如果用jquery，那么将:
	// mouseover 改成 mouseenter
	// mouseout 改成 mouseleave





$(function(){
	$('.menu').hover(function() {
		$(this).find('.list').show();
	}, function() {
		$(this).find('.list').hide();
	});
})

</script>
</head>

<body>

<div class="menu">
	<a href="" class="title">客户服务</a>
	<ul class="list">
		<li>我们是内容</li>
		<li>我们是内容</li>
		<li>我们是内容</li>
		<li>我们是内容</li>
	</ul>
</div>



</body>
</html>
